Tool life testing on a lathe under dry cutting conditions gave ‘n’ and ‘C’ of Taylor tool life equation as 0.12 and 130 m/min, respectively. When a coolant was used, ‘C’ increased by 10%. The increased tool life with the use of coolant at a cutting speed of
(a) 47.4min (b) 37.4min
(c) 27.4min (d) 17.4min